This invention relates to composite hose articles in which the cover and tube are made of dissimilar polymers normally not readily bondable one to the other, and to a method of making such hose.
Oftentimes the mode of failure of both high and low pressure hoses, such as automotive radiator coolant hose, is attack of the embedded reinforcement by the conveyed fluid after permeation through the inner tube layer. EPDM-type terpolymers are being used increasingly as tube stock (and cover stock) in reinforced hose structures particularly because of economic considerations as well as resistance which such terpolymers exhibit against thermal and chemical influences. Despite the fact that EPDM is less permeable to many types of conveyed fluids than more frequently used tube stocks, the problem of permeation through the tube (and eventually completely through the hose) and/or attack of the embedded textile reinforcement remains significant.
An additional problem presented by the use of EPDM-type terpolymers has been the lack of building tack and final adhesivity provided by the terpolymers particularly due to the low unsaturation content and relatively slow cure rates exhibited by the polymers. As a result, there are very few elastomeric materials which will readily bond directly with EPDM-type terpolymers to form composite articles with adequate interfacial adherence.
The most relevant prior art known to Applicants at this time include U.S. Pat. Nos. 3,059,682 to Fischer et al, 3,492,370 to Wirth, 3,651,176 to Usamoto et al, 3,660,224 to Cau et al, 3,682,202 to Buhrmann et al and 3,712,360 to Torti et al.
It is a primary object of the subject invention to provide a composite hose article in which either the tube or cover is made of an EPDM-type terpolymer and is bonded to a dissimilar polymer to which it is not readily bondable, with the aid of an interlayer which additionally and very importantly serves as a fluid barrier internally positioned within the hose wall, also protecting the embedded textile reinforcement.